In the background art, is an automobile mounted with a diesel engine, an exhaust pipe fuel injector is adopted to inject a fuel according to an instructed fuel injection amount to an exhaust upstream side of a diesel particulate filter such that a temperature of the diesel particulate filter is raised to a regenerable temperature and the temperature of the diesel particulate filter is maintained to the regenerable temperature in the regeneration duration, so as to combust a particulate matter collected in the diesel particulate filter (for example, see Patent Literature 1 or Patent Literature 2).